Conventionally, polyamide fibers and polyester fibers have excellent properties for such as yarn strength, antiwearing property, dyeing property, and processing property, and are widely used for clothing use, and industrial material use and the like. Among synthetic fibers, polyamide fibers and polyester fibers, specifically polyamide fibers have high water absorption, but natural fibers have more superior water absorption, and therefore natural fibers are widely used for underwear and the like used in summer season when sweating increases. Furthermore, in order to suppress generation of static electricity in winter season, a fabric having antistatic property has attracted the attention of many people. Moreover, cool-feeling fibers that provide cool feeling upon contact with skin, are also developed as the products which relate to the Cool Biz campaign in summer season.
For example, as antistatic property fibers, fibers with a hydrophilic polymer being incorporated into polyamide fibers or polyester fibers, and fibers with conductive particles, specifically conductive carbon black, being incorporated, have been developed. However, fibers with a hydrophilic polymer being incorporated exhibit antistatic property by absorbing moisture and do not have antistatic effect under a low moisture condition. On the other hand, fibers with conductive particles, specifically conductive carbon black, being incorporated, can be provided with antistatic property even under a low moisture condition, but do not have water absorption and cool feeling by contact.
In order to improve the water absorption and the antistatic property, a technique for conjugating a polyamide and an aliphatic block polyetheramide is disclosed. However, when a large amount of the block polyetheramide is conjugated so as to provide water absorption, color tone of the conjugate fibers becomes intense yellow and the use of the fibers is limited, and the use is also limited in that manufacture cost of the block polyetheramide is expensive. Furthermore, the property of cool feeling by contact is not mentioned (Patent Document 1).
In order to compensate the above-mentioned drawbacks, complete core-sheath type conjugate fibers having a polyether ester amide in the core portion and a polyamide resin in the sheath portion are disclosed, but the fibers have a drawback of having an insufficient water absorbing effect because of the polyether ester amide not exposed on the surface, and further they have only low cool feeling by contact (Patent Document 2).
Fibers made by use of a polyether block amide copolymer are disclosed to have cool feeling by contact (Patent Document 3). However, since the fibers are composed of only a polyether block amide copolymer, although they can have cool feeling by contact, they are not suitable for industrial manufacture, because the polyether block amide copolymer itself easily discolors and it is hard to be dyed and has a high friction.
Furthermore, fibers having antistatic property, water absorption and cool feeling by contact, made of a core-sheath conjugate fiber in which the core portion is composed of a mixture of a polyether ester amide and a polyester are disclosed (Patent Document 4), but they can not have sufficient water absorption and cool feeling by contact since the core portion which provides water absorption and cool feeling by contact is not exposed.
Patent Document 1: JP-B-S44-10488
Patent Document 2: JP-A-H06-136618
Patent Document 3: JP-A-2004-270075
Patent Document 4: JP-A-2005-273085